For a magnetic-storage device such as a hard-disk drive, it is desirable that the areal density of information recorded on a magnetic-recording disk is high so that the hard-disk drive has a large information-storage capacity. One method of achieving ultra-high-density (UHD) magnetic recording is to employ perpendicular-magnetic-recording (PMR), which is a magnetic-recording technology, in which the magnetization of recorded bits is substantially perpendicular to the surface of the magnetic-recording disk. Another magnetic-recording technology for achieving UHD magnetic recording is patterned-medium magnetic recording, in which the recorded information is confined to patterns in the magnetic-recording medium of the magnetic-recording disk.
Two types of patterned media are known: discrete-track media and bit-cell patterned media. For discrete-track media, a groove is provided in between discrete tracks adjacent to each other on the magnetic-recording disk. For bit-cell patterned media, the discrete tracks are further divided into isolated bit cells. Patterned media may reduce the occurrence of writing to adjacent tracks, which increases the areal density of recorded information beyond what is achievable with unpatterned media. Thus, the track density may be increased on magnetic-recording disks that employ patterned media. However, as the track density of recorded information is increased, “adjacent-track interference” (ATI) can still occur, a term of art, which refers to the effect that the writing of information to one track has on the information recorded on an adjacent track. If ATI occurs, information that has already been recorded on an adjacent track becomes partially over-written and the integrity of recorded information cannot be guaranteed.